1. Field of the Invention
The present application relates to sleeves that protect the operation of syringes.
2. Background Information
Syringes are typically cylindrical in shape and equipped with an internally encased piston or piston assembly that pushes a substance within the cylinder and delivers the substance to an output port that is typically a hollow needle. Hereinafter the phrase “piston assembly” is defined to include a single piston and/or a piston assembly made from component parts. The piston is withdrawn from within the cylinder and the cylinder is filled with a substance. The piston is repositioned within the cylinder and pushed towards the output port ejecting the substance through the hollow needle to some desired location.
In applications where the substance is potentially harmful or detrimental, such as cyanoacrilate adhesives or solder paste, or where precise metering of the substance is desired, it is prudent to prevent the substance from leaking around the piston. The piston typically has a seal meant to prevent substances from passing between the piston and the inner cylinder wall, however in some cases, particularly with very viscous substances, the seal may fail and allow leakage of the substance to an area behind the piston.
In some applications, the piston may be operated by a human and leakage around the piston seal may contact the human with potentially harmful results. In other applications the piston-may be pushed via computer controlled device, e.g. a motor and lead screw. In these other applications, however, preventing leakage remains important since the substance within the cylinder may contact the piston advancing means of the computer controlled device and the resulting contamination may then be returned to the computer controlled device itself, potentially causing the device to fail.